In all seriousness -- if you're going to fill a bag with sand, buy the sanitized play sand, not the stuff you'll find for construction uses like mixing into mortar or laying pavers. The sanitized stuff will have the critters killed... The other? You never know what may grow inside your bag.Nice bag! I got the same one from my lovely wife two Xmas's ago. Very well made. I use sand I steal from the local play ground with cat turds and bum urine in it. Perfect density! Haha, JK! I used All-purpose play sand from Home Depot. Works good for how I use it.
I'd still recommended using either rice, beans, or rags. All are more forgiving to your hands.